UPDATE
Just thought I'd tell you all that today, I finally got everything mocked up--and I can confirm that the regular GT/V6 Mustang brakes will work with stock 14" rims. About the only thing holding me back at this point is the fact I don't have the brake kit to cut and reflare new lines for the disc brakes
...but other than that, I'm going to try and have this done before June!
Now, if I don't get distracted by other things...